If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light. But, in 2007, researchers overcame that limit, and created curved beams of light that did not diffract by carefully shaping their waveform.

Now an experiment has used electrons' wave properties to create similar curved beams of electrons. Noa Voloch-Bloch, Yossi Lereah, Yigal Lilach, Avraham Gover, and Ady Arie sent electrons through a holographic film, which shaped their wave characteristics the same way that earlier experiments did for light. Without any additional force, the electrons followed parabolic trajectories while remaining in a tight beam. These paths even "healed" after passing obstacles, restoring their shape as though the objects were not there.

According to quantum physics, particles and waves are two aspects of the same system. The trajectory of a particle is actually governed by its quantum-mechanical wave function, which gives the probability for a particle may be found at a particular position. Waves traveling through an aperture, for example, will interfere with themselves, producing a gradually spreading beam where the particles follow diverging paths; that's diffraction. Lasers, flashlights, and the like send light through an opening, and so all they experience diffraction.

Creating curved trajectories—known as Airy beams—is a matter of manipulating the quantum wave function. In an Airy beam, waves interfere in a way that ensures particles are most likely to trace parabolic trajectories rather than straight lines. Because the entire wave function behaves differently than it does under ordinary circumstances, the particles no longer diffract—meaning Airy beams also maintain their intensity over large distances.

Dodging Isaac Newton

In Newton's laws of motion, a particle will travel in a straight line at a steady speed unless an external force acts on it; you need a constant net external force to produce parabolic trajectories from Newtonian perspective. In quantum physics, the wave function still obeys a form of Newton's laws. The statistical average of a wave function (its centroid) still tracks a straight line when there is no external force. The key thing is that the probability of finding a particle at a given position may not follow the same line.

Electrons also experience diffraction and interference, which is the source of the famous quantum double-slit experiment. In the new experiment, the researchers manipulated the wave function of an electron beam by sending it through a specific holographic pattern. They focused the beam using a magnetic field that acted much like a lens, producing a distinctive triangular bundle of electron beams. Each bundle followed a curved path, which the researchers determined by measuring the electron patterns at various distances from the hologram.

One strange consequence of Airy beams is their ability to self-heal. When the electron Airy beam reached a glass wire that partly blocked its path, the trajectories compensated for the barrier, ultimately producing exactly the same pattern with or without the obstacle in place.

Previous research on Airy beams of light has shown they can be shaped in a number of arbitrary ways, and maintain their coherence over large distances. The new results suggest the same thing is true for electrons. Shaped, diffraction-free electron beams would be extremely useful in tunneling electron microscopes (TEMs), commonly used to manipulate and image the surface properties of materials. Long-range coherent beams would also be handy for studying the properties of the electrons themselves, including their interactions within atoms.

How about a particularly intense, airy beam that follows a parabolic trajectory from one country to another, allowing very precise long range attack? Is that possible?

I was going to say wireless power transmission, but your idea is more likely to get DARPA funding.

I am far from being an expert in electron beams and vacuum science, although I do use them, but I believe that one problem with electron beams is that they only work well in vacuum. I would think that you would need to build a long, curved glass tube from the US to North Korea and evacuate all of the air out of it to make a weapon and if you want to transmit power, you may as well run a wire. It's not practical at all.

How about a particularly intense, airy beam that follows a parabolic trajectory from one country to another, allowing very precise long range attack? Is that possible?

I was going to say wireless power transmission, but your idea is more likely to get DARPA funding.

I am far from being an expert in electron beams and vacuum science, although I do use them, but one problem with electron beams is that they only work in vacuum. I would think that the you would need to build a long, curved glass tube from the US to North Korea and evacuate all of the air out of it to make what you are talking about.

I think the reference was more to the Airy Beam concept in general, which should equivalently apply to laser light or some other electromagnetic wave.

How about a particularly intense, airy beam that follows a parabolic trajectory from one country to another, allowing very precise long range attack? Is that possible?

Not really, no, at least as I understand it. The beam path is the result of a bunch of different waves adding constructively along the path, and destructively elsewhere. At long ranges you'll need absolutely massive amounts of input energy. Secondly, it actually ends up forming a pattern of beams, not a single one, which might not be a problem but likely would at that energy levels. And you'd still have atmospheric distortion disturbing the beams, since they disturb the waves. It can go around obstacles because the beam is formed by many different waves, most of which don't have to pass through the obstacle.

Ruckus Wireless WiFi Access Points work exactly the same way, using up to 20 antennas to create the best possible pattern, out of 4,000 diff patterns, to steer the WiFi signal and reach the user, be it behind a column, microwave oven, or any other obstacles or interference. They can track you in 3D space, and has a table, per user, remembering the patterns that work best for that particular user, providing the most consistent signal.

Disclosure: This is not an Ad. Tho I do sell such equipment. However I think its relevant for the article as it does use the wave nature of the electromagnetic signal to create interference patterns that look very much like the one in the picture.

Does this have any impact on fiber optic communications? I'm wondering if you shaped a signal into an Airy beam before broadcasting it through a fiber optic cable, would it propagate over longer distances?

Does this have any impact on fiber optic communications? I'm wondering if you shaped a signal into an Airy beam before broadcasting it through a fiber optic cable, would it propagate over longer distances?

It would not even function most likely. I do not have much experience with airborne lasers, but I have a lot of experience with fiber optics (Used to design transmitters and receivers).

Depending on the wavelength and fiber type used, any sort of air gap between the laser and the fiber causes significant distortion. Mostly related to back reflections and SBS distortion. SBS coming in at longer wavelengths (~1450nm and higher getting worse as the wavelength gets longer).

So really even if you could shoot an airy beam into fiber, the limiting factor in long haul fiber is distortion caused by the light passing through the fiber.

Does this have any impact on fiber optic communications? I'm wondering if you shaped a signal into an Airy beam before broadcasting it through a fiber optic cable, would it propagate over longer distances?

The individual photons don't curve. The holographic filter merely produces a region of high intensity that follows a curved path. Think back to the old double slit experiment. It produces an interference pattern, with oscillating regions of high and low intensity. This is the same exact thing, but instead of a pair of slits, the holographic filter is specially designed to produce a curve. You are emitting photons/electrons that are filling the entire area, but constructive and destructive interference means they only manifest themselves along that curve. It's "self healing" not because the beam somehow travels through the object, but because the lightfield recreates the beam on the opposite side, when it is no longer shadowed by the object. Just like a Bessel beam, a true Airy beam would require infinite power and an infinite baseline.

Can someone explain how a beam can trace a parabolic curve without a force acting on the particles? Seems to be a violation of the conservation of energy or one of Newtons laws or something.

If I understood correctly, you have diverging distribution nodes, all part of the same beam (the beam is a series of nodes). But the intensity and width of the nodes (at least for the biggest one) are stable, while the distance between the node increase non linearly => the main node has a curvy trajectory.

Can someone explain how a beam can trace a parabolic curve without a force acting on the particles? Seems to be a violation of the conservation of energy or one of Newtons laws or something.

The particles that make up the beam do not curve. Only the beam itself curves. The holographic filter produces an electron field with constructive and destructive interference set up such that the particles only manifest themselves as they travel through the path of the curved beam.

If I understand this correctly, an Airy beam is basically a hologram of a curve? The precise shape of the curve takes advantage of the wavelength to be particularly coherent at the far end of the hologram.

If this is true, the airy beam can't manifest unless it has (straight) line-of-sight to the emitter. Thus we can't reproduce this effect:

If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light.

Isn't that wrong? The angle of a flashlight generally has nothing to do with diffraction.

If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light.

Isn't that wrong? The angle of a flashlight generally has nothing to do with diffraction.

I agree. That's not diffraction. However, instead of using the wrong definition, I think the writer left out a word or two and meant to say, "If you shine a beam of light from a laser of flashlight through a small slit..."

If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light.

Isn't that wrong? The angle of a flashlight generally has nothing to do with diffraction.

I agree. That's not diffraction. However, instead of using the wrong definition, I think the writer left out a word or two and meant to say, "If you shine a beam of light from a laser of flashlight through a small slit..."

No, diffraction is the correct term, and applies in both those cases. The opening of a flashlight or laser from which the light emerges is, in effect, as it pertains to diffraction, a slit.

Yes the beam width of a flashlight beam is dominated not by diffraction but by the size of the aperture and distance from the bulb. But the width of that beam will be wider than it you simply considered the shadow cast by the edge of the aperture. And for a laser, diffraction is why they will always have non-zero beam divergence.

Shining these beams through a second opening farther away only allows you to make the diffraction more apparent.

What I took away from this was that with a powerful-enough LASER (because LASER is an acronym[caps]) we should now be able to fire light several times around the earth, if we aim it right and the curve is proper.

*Points light in proper direction**watches several hundred beams appear from both in front and behind him*

I am pretty sure that a Tunneling Electron Microscope (which works by rastering/scanning) is abbreviated STM (Scanning Tunneling Microscopy). Following on that, this is done by rastering a sharp tip VERY close to a sample surface (a few nm, sometimes less), applying a bias and observing the tunneling current. I am not sure how this sort of beam would benefit here as you don't really have a beam (at least thats not how I think of it) and you certainly don't have room to pass your probe through a hologram to shape the probe's wavefront.

TEM is the commonly used abbreviation for Transmission Electron Micrsocopy and as it so happens here we have a beam and diffraction is a fundamental phenomena we observe directly and use to form both diffraction patterns and is one mechanism of contrast production in the image plane. I believe this article might confuse to two techniques.

Both techniques are done in various states of vacuum (STM usually UHV), TEM in HV. Generally speaking, in TEM, the current limitations come from electromagnetic lens abberations, though diffraction off of aperture edges does come into play in certain imaging conditions. Beam spatial coherency ultimately limits maximum imaging resolution (currently >0.5Å) so I would be curious to see if an Airy beam could push this further. Also, the self-healing aspects of such a beam would be put to a test as your beam passes through a solid sample.

I'm curious to get a look at the paper tomorrow and hope that my simple Materials Scientist mind can understand all of the whacky physics.

If I understand this correctly, an Airy beam is basically a hologram of a curve? The precise shape of the curve takes advantage of the wavelength to be particularly coherent at the far end of the hologram.

If this is true, the airy beam can't manifest unless it has (straight) line-of-sight to the emitter. Thus we can't reproduce this effect:

No cats were harmed during the composition of this post.

I think you are correct Frank. The curving path of the beam is really more a way of describing its appearance, not a good description of the extent of the whole electromagnetic field. You can't make light go around a corner or over the horizon this way. You can shine a beam past a barrier that is substantially smaller than the size of the whole field, but not one that blocks the whole straight line path of all parts of it.

If you shine a beam of light from a laser or flashlight, the beam will spread out over distance, becoming wider and less intense far from the source. That phenomenon is called diffraction, and it is one of the fundamental aspects of the wave nature of light.

Isn't that wrong? The angle of a flashlight generally has nothing to do with diffraction.

I agree. That's not diffraction. However, instead of using the wrong definition, I think the writer left out a word or two and meant to say, "If you shine a beam of light from a laser of flashlight through a small slit..."

Haha.. This is it. That's the right definition alright. Many thanks to Mr. Matthew Francis for explaining what diffraction is. A definition I was missing out on other thread. <recap> Supposedly a supernova occurred 27,000 light years away and my argument was there was only few photon atom actually got to Earth even photon atom keep on going forever but it is because light "becoming wider and less intense far from the source." only very few, one or two photon atom might have actually hit right at Earth 1,000 years ago. And that was this argument from me. Hey, thanks Matt. :-)

I'm willing to bet that their BeamFlex™ technology, as clever as it is, does not create curved, self-healing, non-diffracting beams, such as described in this article.

Hmmm, and here I thought they worked the same way. So in BeamFlex it interferes with the signal from another antenna, but in this case it interferes with itself due to alignment through the hologram?

In fairness, there are some similarities between beamforming technology and an Airy beam, in that they both rely on a combination of constructive and destructive interference. An important difference is that beamforming uses multiple signal sources (antennae), while an Airy beam has a single signal source passed through a holographic filter.

I don't know whether or not this will be helpful (or even entirely accurate), but I think of an Airy beam as being analogous to a car on a straight road; the road is the beam, and the path that the car follows is the high-intensity region of the beam. The car starts its journey slightly to the (for example) left of the centre line. As it travels, it drifts over to the right side, then drifts back to the left again. Overall, the beam as a whole is straight, but the high-intensity region of the beam is curved.

Of course, that analogy breaks down when the high-intensity part of the beam encounters an obstacle... then the car becomes more like a swarm of bees, flowing round the obstacle and re-forming once it is past it.

Ruckus Wireless WiFi Access Points work exactly the same way, using up to 20 antennas to create the best possible pattern, out of 4,000 diff patterns, to steer the WiFi signal and reach the user, be it behind a column, microwave oven, or any other obstacles or interference. They can track you in 3D space, and has a table, per user, remembering the patterns that work best for that particular user, providing the most consistent signal.

Reading that i found myself reminded of a "recent" article where multiple sender antennas were used so that locally their signals would destructively interfere and so allow the nearby receiver antenna to still pick up distant senders. Meaning that you could send and receive at the same time.

How about a particularly intense, airy beam that follows a parabolic trajectory from one country to another, allowing very precise long range attack? Is that possible?

Nope. Even ignoring the power concerns, you would need to maintain coherence over the whole distance, and nonuniformity in the atmosphere is going to prevent that from happening, even if you had a pure source.

How about a particularly intense, airy beam that follows a parabolic trajectory from one country to another, allowing very precise long range attack? Is that possible?

Nope. Even ignoring the power concerns, you would need to maintain coherence over the whole distance, and nonuniformity in the atmosphere is going to prevent that from happening, even if you had a pure source.

An even bigger problem is that while the region of maximum intensity within the beam is curved, the beam as a whole is straight, so regardless of the presence (or otherwise) of an atmosphere you couldn't aim it at anything that was over the horizon.